Optical hard coats are applied to optical display surfaces to protect them from scratching and marking Desirable product features in optical hard coats include durability to scratches and abrasions, and resistance to inks and stains.
Materials that have been used to date for surface protection include fluorinated polymers, or fluoropolymers. Fluoropolymers provide advantages over conventional hydrocarbon based materials in terms of high chemical inertness (solvent, acid, and base resistance), dirt and stain resistance (due to low surface energy), low moisture absorption, and resistance to weather and solar conditions.
Fluoropolymers have also been investigated that are crosslinked to a hydrocarbon-based hard coating formulation that improves hardness and interfacial adhesion to a substrate. For example, it is known that free-radically curable perfluoropolyethers provide good repellency to inks from pens and permanent markers when added to ceramer hard coat compositions, which comprise a plurality of colloidal inorganic oxide particles and a free-radically curable binder precursor, such as described in U.S. Pat. No. 6,238,798 to Kang, and assigned to 3M Innovative Properties Company of St. Paul, Minn.
Industry would find advantage in other fluoropolymer-based hard coatings, particularly those having improved properties.